The preventive effects of taurine on neural tube defects through the Wnt/PCP-Jnk-dependent pathway

Excessive apoptosis and ROS induced by ethionine affect neural cell viability and differentiation

The central nervous system (CNS) diseases are still a major cause of morbidity and mortality throughout the world, which imposes heavy burden on the development of society. Ethionine is a non-proteinogenic amino acid having similar chemical structure and activity to that of methionine, with which it competes. Previous studies have confirmed that ethionine affects various cellular functions by inhibiting the biosynthesis of proteins, RNA, DNA, and phospholipids, or all of them. The relationship of ethionine with some CNS diseases, including neural tube defects, has been investigated recently. However, the detailed effects of ethionine on the nerve cell bioactivities and the underlying mechanisms have not been fully explored. Herein, we systematically investigated the influences of ethionine on the proliferation, differentiation, and apoptosis of neural stem cells (NSCs) and post-mitotic nerve cells. We demonstrated that ethionine inhibited cell viability by disrupting the balance between proliferation and apoptosis, prevented NSCs from differentiating into neurons and astrocytes, and blocked cell progression from G1 to S phase via reducing cyclin D1 function in nerve cells including NSCs, a mouse hippocampal neuron cell line (HT-22), and a mouse brain neuroma cell line (Neuro-2a). We speculated that the inhibitory effect of ethionine on cell viability and differentiation are associated with increased reactive oxygen species production. Our results also supported the concept that ethionine may be an underlying cause of abnormal folate metabolism-induced CNS diseases. Our findings may provide important direction for the application of abnormal folate metabolism-induced CNS diseases in future NSC-based therapies.

Upregulation of Prickle2 Ameliorates Alzheimer's Disease-Like Pathology in a Transgenic Mouse Model of Alzheimer's Disease

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder that has no effective therapies. Prickle planar cell polarity protein 2 (Prickle2), is an important cytoplasmic regulator of Wnt/PCP signaling. It has been reported that Prickle2 deficiency reduced neurite outgrowth levels in mouse N2a cells and led to autism-like behaviors and hippocampal synaptic dysfunction in mice. However, much less is known about the relationship of Prickle2 to AD pathogenesis. RT-qPCR, Western blot and IHC results showed that the mRNA and protein levels of Prickle2 were reduced in APP/PS1/Tau transgenic (3xTg) mice. Intravenous injection of Prickle2-overexpressing AAV-PHP.eB vectors improved the cognitive deficits in 3xTg mice. We also demonstrated that Prickle2 could repress oxidative stress and neuroinflammation, ameliorate the amyloid β (Aβ) plaque pathology and reduce Tau hyperphosphorylation in APP/PS1 mice. Further investigation of the mechanism of Prickle2 in AD revealed that Prickle2 inhibited Wnt/PCP/JNK pathway in vivo and in vitro. Our results suggest that Prickle2 might be a potential candidate for the diagnosis and treatment of AD.

sFRP1 protects H9c2 cardiac myoblasts from doxorubicin-induced apoptosis by inhibiting the Wnt/PCP-JNK pathway

Doxorubicin (Dox) is an effective chemotherapy drug against a wide range of cancers, including both hematological and solid tumors. However, the serious cardiotoxic effect restricted its clinical application. We previously have illuminated the protective role of canonical Wnt/β-catenin signaling in Dox-induced cardiotoxicity. Secreted frizzled-related protein 1 (sFRP1) is one of the endogenous inhibitors of both canonical and noncanonical Wnt signaling. In this study, we investigated the relationship between sFRP1 and noncanonical Wnt/PCP-JNK (Wnt/planar cell polarity-c-Jun N-terminal kinase) pathway in Dox-induced cardiotoxicity in vitro and in vivo. We showed that treatment of H9c2 cardiac myoblasts with Dox (1 μM) time-dependently suppressed cell viability accompanied by significantly decreased sFRP1 protein level and increased Wnt/PCP-JNK signaling. Pretreatment with SP600125, the Wnt/PCP-JNK signaling inhibitor, attenuated Dox-induced apoptosis of H9c2 cells. Overexpression of sFRP1 protected H9c2 cells from Dox-induced apoptosis by inhibiting the Wnt/PCP-JNK pathway. After intraperitoneal injection of a cumulative dose of 15 mg/kg Dox, rats displayed significant cardiac dysfunction; their heart showed inhibited Wnt/β-catenin signaling and activated Wnt/PCP-JNK signaling. These results suggest that sFRP1 may be a novel target for Dox-induced cardiotoxicity.

Taurine and its analogs in neurological disorders: Focus on therapeutic potential and molecular mechanisms

Taurine is a sulfur-containing amino acid and known as semi-essential in mammals and is produced chiefly by the liver and kidney. It presents in different organs, including retina, brain, heart and placenta and demonstrates extensive physiological activities within the body. In the several disease models, it attenuates inflammation- and oxidative stress-mediated injuries. Taurine also modulates ER stress, Ca2+ homeostasis and neuronal activity at the molecular level as part of its broader roles. Different cellular processes such as energy metabolism, gene expression, osmosis and quality control of protein are regulated by taurine. In addition, taurine displays potential ameliorating effects against different neurological disorders such as neurodegenerative diseases, stroke, epilepsy and diabetic neuropathy and protects against injuries and toxicities of the nervous system. Several findings demonstrate its therapeutic role against neurodevelopmental disorders, including Angelman syndrome, Fragile X syndrome, sleep-wake disorders, neural tube defects and attention-deficit hyperactivity disorder. Considering current biopharmaceutical limitations, developing novel delivery approaches and new derivatives and precursors of taurine may be an attractive option for treating neurological disorders. Herein, we present an overview on the therapeutic potential of taurine against neurological disorders and highlight clinical studies and its molecular mechanistic roles. This article also addresses the neuropharmacological potential of taurine analogs.